The trabecular meshwork of the eye is a principal site of outflow resistance to the aqueous humor. The trabecular meshwork is subjected to stretching by the ciliary muscle. In an effort to understand the effects of mechanical stretch on the trabecular meshwork, we have grown human trabecular meshwork cells on silicone sheets and then stretched them by 10%. The cells have an altered morphology and are elongated when their support is stretched. Besides a rapid change in tyrosine phosphorylation on several proteins, there is a prominent change in the organization of actin within the cytoplasm. One of the proteins closely lined to actin polymerization, alpha B-crystallin, rapidly disappears from the cell. Over the next six hours, the shape and actin organization of the cell returns to the appearance of unstretched cell. The level of alpha B-crystallin starts to return to control levels at this time. This crystallin may be an important component in stabilizing actin filaments. The dynamic change in the cytoskeleton is also matched by changes in the signal transduction pathways within the cells. There is a down regulation of the MAP kinase pathway while the Jun kinase remains at nearly constant levels. These pathways influence transcription of genes within the cell and may alter the types of proteins that the cell subsequently synthesizes. Our hypothesis is that the trabecular meshwork cells attempt to maintain their focal contact while the cells are being stretched and then must rearrange their contacts as well as modify their cytoskeleton over time. The stretching and rearrangement leads to alteration in signal transduction pathways that changes protein expression in the cells. These changes in protein expression may be important in understanding changes with some types of glaucoma since the trabecular meshwork is highly stretched in this disease.